Multiple output magnetic core circuit



May 29, 1962 H. D. CRANE ETAL MULTIPLE OUTPUT MAGNETIC CORE CIRCUIT Filed June l2, 1958 MULTIPLE GUTPUT MANETIC CORE CIRCUT Hewitt D. Crane, Palo Alto, David R. Bennion, Loma Mar, and Fred C. Heinzmann, Palo Alto, Calif., aS-

signors to Burroughs Corporation, Detroit, Mich., a

corporation of Michigan Filed .lune 12, 1958, Ser. No. 741,690 9 Claims. (Cl. 340-174) This invention relates to magnetic core storage and transfer circuits, and more particularly is concerned with a magnetic core circuit in which binary information can be simultaneously transferred from one core element to a plurality of core elements.

in copending application Serial No. 698,633 tiled November 25, 1957, and now abandoned in the name of Hewitt D. Crane and assigned to the assignee of the present invention, there is described a core register having a novel transfer circuit requiring no diodes or other impedance elements in the transfer loops between cores. The basic binary storage element of this circuit is au annular core having an input aperture and output aperture therein. The binary Zero digits are stored in the form of flux oriented in the same direction in the core on either side of the respective apertures, while the binary one digits are stored in the form of flux extending in opposite directions on either side of the respective apertures. Transfer is effected by applying a current pulse of predetermined magnitude to a coupling loop linking one aperture in each of two cores, one core constituting a transmitting core and the other core constituting a receiving core.

The present invention utilizes the principles of the above-identified copending application to transfer binary information stored in a core element simultaneously to a plurality of receiving core elements. While the abovementioned copending application teaches that a transmitting core element may have a plurality of outputs providing nondestructive readout to a number of output circuits, transfer from each output requires its own transfer pulse and readout from the several outputs cannot be readily effected simultaneously. The present invention has the advantage that readout can be effected from a transmitting core element to a plurality of receiving core elements simultaneously in response to a single transfer pulse. This permits transfer to auxiliary output cores from any of the core elements in a shift register, for example.

ln brief, the circuit of the present invention comprises a single transmitting core element and a plurality of receiving core elements. Each of the core elements is made of magnetic material, such as ferrite, having high iiux retentivit-y, the core elements preferably being annular in shape to provide a relatively long closed uX path and having at least two small `apertures therein defining relatively short flux paths. Means including windings on each of the core elements is provided for selectively clearing the transmitting core element and the receiving core elements by saturating the flux around the relatively long flux paths of the respective core elements in one direction. A transfer circuit including a winding linking the transmitting core element through one of said apertures is connected in shunt with the series connected windings respectively linking the receiving core elements through said apertures. Transfer of binary information from the transmitting core to each of the receiving cores is effected by first clearing the receiving cores and then pulsing a current through the transfer circuit, the current level in the winding linking the transmitting core being held below the threshold required to switch flux around the relatively long flux path but above the threshold required to switch flux around the relatively short flux path. If a Vnited States Patent "a Patented May 29, 1962 binary one has been stored in the transmitting core, pulsing of the transfer circuit will cause flux to be switched in the receiving cores, establishing a binary one ux condition in each of the receiving core elements.

For a better understanding of the invention, reference should be had to the accompanying drawings, wherein:

FIGS. 1 and 2 show a ferrite magnetic core element such as used in the present invention in two conditions of iuX orientation; and

FIGS. 3 and 4 vshow alternative circuits according to the present invention for transmitting information from a single transmitting core element to a pair of receiving core elements of the type shown in FIGS. l and 2.

Consider an annular core, such as indicated `at 10 in FIGS. l and 2, made of a magnetic material such as ferrite, having a square hysteresis loop, i.e., a material having high flux retentivity or remanence. The annular core is preferably provided with two small `apertures 12 and 14, each of which divides the annular core into two parallel flux paths as indicated by the arrows. If a large current is pulsed through the central opening in the core tu, as lby a cleaiing winding 16, the flux in the core may be saturated in a clockwise direction. The core is then said to be in a cleared or `binary zero condition. If a large current is passed through either of the -apertures 12 or 14, as by either of the windings 18 and 20, in the direction indicated in FIG. 2, and the current is of sutlicient magnitude to cause switching of flux around the central opening of the'annular core, ya portion of the flux can be reversed so that the flux extends in opposite direction on either side of the respective apertures 12 and 14, as indicated by the arrows in FIG. 2. The core is then said to be in the set or binary one state.

The signicant aspect of the transfer circuit described in the above-identified copending application is that with a given number of turns linking one of the small apertures in the core and with the core in its cleared state as shown in FlG. l, a current exceeding a threshold value It must be provided to change the core to its set state as shown in FIG. 2. If the current does not exceed this threshold level, substantially no flux is switched around the core. The aperture is said to be blocked when the current passing through the `aperture must exceed the threshold value It in order to switch any flux in the core element.

On the other hand, if the core is already in its set state, a very small current, substantially less than the threshold value It, causes ux to switch locally about the aperture. In this case the aperture is said to be unblocked Thus if a current slightly less than the threshold value current It is passed through an aperture in a core element, flux will be switched or not switched within the core depending upon whether the core is in its cleared state or its set state, i.e., depending on whether the aperture is blocked or unblocked.

This principle is used to provide a multiple output core circuit as shown in FIG. 3. First, consider a transmitting core element 22 having an input aperture 24 and an output `aperture 26. The transmitting core element 22 is coupled to a similar receiving core element 28 having an p input aperture 30 and an output aperture 32. Each of the core elements 22 and 28 is provided with a clearing winding which passes current through the central opening of the core element, as indicated at 34 and 36 respectively. Suitable means is provided for generating clearing pulses through the respective-windings 34 and 36, as by means of clear pulse sources indicated at 38 and 40 respectively. Thus each of the core elements 22 and 28 may be placed in the cleared state in which all of the flux is saturated in a clockwise direction in the manner described above in connection with FIG. 1. The output aperture 26 of the core element 22 is now blocked, as is the output aperture 32 of the core element 28.

A transfer loop 42 links the core element 22 by means of a winding 43 passing through the output aperture 26 to the core element 28 by means of a winding 45 passing through the aperture 30. Assume for the present that the windings 43 and 45 are directly connected in parallel, as by a jumper, indicated by the dotted lines at 47. A transfer pulse source 44, having a constant current characteristic, is coupled across the transfer loop 42. With both the core elements 22 and 2S in their cleared state, the current flow produced by the transfer pulse source 44 divides between the portion of the loop 42 linking the output aperture 26 and the portion of the loop linking the aperture 30. The resistance in the two windings in the loop 42 is preferably arranged so that a substantially equal number of ampere-turns links the core 22 and the core 23. The current split is' such that the current through each branch of the loop 42 is below the threshold required to switch flux in the respective cores. As a result, with both the cores cleared, a transfer pulse has no effect on either core.

If, however, a large current has been pulsed through the input aperture 24 of the transmitting core element 22 so as to put the core element 22 in its set state and unblock the output aperture 26, corresponding to the ux condition shown in FIG. 2, a different result takes place when a transfer pulse is generated by the source 44. In the latter case a much smaller current is required to reverse linx locally about the unblocked output aperture 26 in the transmitting core 22. As a result, with the core 22 in its set state, when a transfer pulse is applied across the loop 42, the current through the aperture 26 is sufficiently large to switch ux locally about the aperture 26. The impedance of the branch of the transfer loop 42 linking the aperture 26 is thereby momentarily increased due to the counter E.M.F. generated by the switching ilux. -As a result, the current through the branch of the transfer loop 42 linking the receiving core element 28 through the aperture 30 increases above the threshold level required to switch flux about the central opening of the annular core element 28. As a result the core element 28 is left in its set state, following a transfer pulse from the source 44, when the transmitting core 22 is initially in its set state, hereby unblocking the output aperture 32.

According to the present invention, to provide an additional output, a second receiving core element 46 is pro vided. The clearing winding 36 from the source 40 may he arranged to link the second receiving core element 46 also, for simultaneously clearing both of the receiving cores. The second receiving core element 46 is provided with an input aperture 48 and an output aperture 50. A winding 52 links the core element 46 through the aperture 48. The winding 52 is connected in series with the winding 45 linking the input aperture of the core element 28.

Both of the receiving core elements 2S and 46 are provided with separate output windings 54 and 56 respectively, linking the apertures 32 and 50. These output windings may form part of closed loops which may be simultaneously pulsed from a transfer pulse source 58 identical to the pulse source 44.

The several windings forming the loop 42 are of very low resistance, comprising for example a single turn linking the receiving core elements and two turns on the transmitting winding. In general, the turns linking the transmitting core element should be equal to or greater than the total turns linking all the receiving core elements. The current passing through the winding 43 is below the threshold level It, and with the aperture 26 blocked, the current passing through the series windings 45 and 52 is also below the threshold level It. Therefore the advanced pulse does not change the ux condition of either the transmitting core element or the two receiving core elements.

However, if the output aperture 26 of the transmitting core element 22 is unblocked, corresponding to the binary one ux condition, the impedence of the winding 43 will be momentarily increased by the local switching of flux around the aperture 26. The resulting increase of current through the windings 4S and 52 in series exceeds the threshold level for these two core elements, resulting in flux being switched around the relatively long path formed by the annular shape of the receiving core elements. As a result the output apertures 32 and 50 respectively are unblocked. Therefore when a transfer pulse from the source 58 is applied across the windings 54 and 56, binary one information can be transferred to separate outputs from the core elements 28 and 46 respectively.

It will be seen that a complete cycle of transfer from the core element 22 to the two outputs requires four basic clock pulses in sequence. These pulses may be derived from a suitable pulse source 60 coupled to a delay line 62 having four output taps. The output pulses derived from the delay line 62 are successively coupled to the advance pulse source 44, the clearing pulse source 38, the transfer pulse source 58, and the clearing pulse source 40. This is the same identical sequence provided in the shift register described in the above-mentioned copending application.

As shown in FIG. 4, the receiving core elements 28 and 46 can be connected with their input windings 45' and 52 connected in parallel instead of in series. In this case, each receiving core element may have the same number of turns or less in the input winding than the turns linking the output of the transmitting core element 22. However, the advance current level from the transfer pulse source must be increased over what is required with one receiving core element. With two units of advance current, each unit being equal to It, required for a single receiving core element, then in general n+1 units are required for n receiving core elements having their input windin g connected in parallel.

From the above description it will be recognized that with the same basic clock pulse sequence required for shifting information in a single chain of core elements. an additional output can be provided associated with each core element in the chain. While the circuit as shown in FIGS. 3 and 4 describe a pair of output core elements associated with each transmitting core element, in principle, more than two output core elements can be provided if desired.

What is claimed is:

l. A magnetic core storage circuit comprising a single input core element and a plurality of output core elcrnents of magnetic material having a high flux remanence, each of the core elements being annular in shape with a central opening, an input aperture and output aperture extending through each core element, means including a winding linking the input core element through the central opening for clearing all the flux to saturation in one direction in the input core element, whereby the output aperture is blocked, an input winding linking the input core element through the input aperture for unblocking the output aperture in response to an input signal, means including windings linking the output core elements for clearing all the flux to saturation in one direction in the output core elements, a transfer circuit coupling the input core element to each of the output core elements, the transfer circuit including windings linking each of the output core elements through the input apertures thereof and a winding linking the input core element through the output aperture thereof, the windings linking the output core elements being connected in series and the winding linking the input core element being connected in parallel with the series connected windings to form two parallel current paths, and means for applying a transfer pulse across the parallel connected windings of the transfer circuit, the pulse being of a magnitude to produce a current iiow in the two parallel current paths of the transfer circuit that is below the threshold current level required to switch flux in the respective cores when the output aperture of the input core element is blocked.

2. A magnetic core storage circuit comprising a single input core element and a plurality of output core elements of magnetic material having a high ux remanence, each of the core elements being annular in shape with an input aperture and an output aperture extending through each core element, means for clearing all the flux to saturation in one direction in the input core element, whereby the output aperture is blocked, means for clearing all the flux to saturation in one direction in the output core elements, a transfer circuit coupling the input core element to each of the output core elements, the transfer circuit including windings linking the input core element through the output aperture and each of the output core elements through said input apertures, the windings linking the output core elements being connected in series and the winding linking the input core element being connected in parallel with the series connected windings to form two parallel current paths, and means for applying a transfer pulse across the parallel connected windings of the transfer circuit.

3. A magnetic core circuit comprising a plurality of output core elements and a single input core element, each of said core elements being made of magnetic material having a high flux retentivity, the core elements further being annular in shape and having at least two small apertures therein, an input winding linking one aperture of the input core element, an output winding linking one aperture of each of the two output core elements, each of the core elements having a transfer winding linking the annular core element through the other of said two apertures, the transfer windings linking the output core elements being connected in series with each other and in parallel with the transfer winding linking the input core element across a pair of terminals, and means for applying a transfer pulse between said terminals.

4. A magnetic core circuit comprising a plurality of core elements of magnetic material having high flux remanence, each core element having a plurality of apertures, a transfer circuit including a single output winding in shunt with a plurality of series connected input windings to form two parallel current paths, each of the core elements being linked by a respective winding in the transfer circuit through one of said apertures, means for blocking the apertures of the core elements linked by the windings of the transfer circuit to prevent switching of flux in any one of the associated core elements by current providing a predetermined ampere-turns threshold ylevel passing through the respective windings in the transfer circuit, means for selectively unblocking the aperture linked by said single output winding in the transfer circuit, and means for applying current through each of said parallel current paths of the transfer circuit having a level below the level of said current providing a predetermined ampere-turns threshold level.

5. A magnetic core storage and transfer circuit for transfer of information from a single storage element simultaneously to a plurality of storage elements comprising a single transmitting magnetic core element and a plurality of receiving magnetic core elements having a high flux remanence characteristic, each of the core elements having a large opening defining a relatively long closed uX path around the opening and two small apertures each defining a relatively short flux path around the respective apertures, means for clearing all the flux around the relatively long flux path of the transmitting core element in one direction, means for clearing all the ux around the respective relatively long flux paths of the receiving core elements in one direction, a transfer circuit including a winding linking the transmitting core element through one of said small apertures and windings respectively linking the receiving core elements through one of said small apertures in each of the receiving core elements, the winding linking the transmitting core being connected in parallel with the windings linking the receiving cores, whereby two parallel current paths are provided, one current path linking the transmitting core and the other current path linking the receiving cores, means for passing a current through the transfer circuit providing a current level in the path linking the transmitting core that is below the threshold required to switch flux around the relatively long flux path in the transmitting core but above the threshold required to switch flux around the relatively short flux path in the transmitting core, an input winding linking the transmitting core through the other of said apertures, output windings respectively linking the receiving cores through the other of said apertures, and means for successively pulsing the means for clearing the receiving core elements and the means for passing current through the transfer circuit.

6. A magnetic core circuit comprising a plurality of output core elements and a single input core element, each of said core elements being made of magnetic material having a high iluX retentivity, the core elements further being annular in shape and having at least two small apertures therein, each of the core elements having input and output windings linking the annular core element respectively through said two apertures, two of the windings linking the output vcore elements being connected in parallel with one of the windings linking the input core clement across a pair of terminals, and means for applying a transfer pulse between said terminals.

7. A magnetic core storage circuit comprising a single input `core element and a plurality of output core elements of magnetic material having a high flux remanence, each of the core elements being annular in shape,

' the output core elements each having an input aperture and the input core element having an output aperture, means for clearing all the flux to saturation in one direction in the input core element, whereby the output aperture is blocked, means for clearing all the flux to saturation in one direction in the output core elements, a transfer circuit coupling the input core element to each of the output core elements, the transfer circuit including windings linking the input core element through the output aperture and each of the output core elements through said input apertures, the windings linking the output core elements being connected in parallel with the winding linking the input core element, and means for applying a transfer pulse across the parallel connected windings of the transfer circuit.

8. Apparatus as dened in claim 7 wherein the windings of the transfer circuit linking the output core elements are connected in parallel with each other.

9. Apparatus as defined in claim 8 wherein the windings in the transfer circuit have substantially equal numbers of turns.

References Cited in the le of this patent UNITED STATES PATENTS 2,781,503 Saunders Feb. 12, 1957 2,802,953 Arsenault et al. Aug. 13, 1957 2,818,555 Lo Dec. 31, 1957 2,818,556 Lo Dec. 31, 1957 2,889,542 Goldner et al. June 2, 1959 2,896,194 Crane July 21, 1959 2,898,581 Post Aug. 4, 1959 2,902,676 Brown Sept. 1, 1959 OTHER REFERENCES The Transiluxor by Rajchman and Lo, published in Proceedings of the IRE, March 1956, pp. 321-332.

Flux Shifting Device by Bauer and Butler, published in IBM Technical Disclosure, vol. I, No. 2, August 1958, p. 33. 

